--- a/sway/ipc-json.c
+++ b/sway/ipc-json.c
@@ -3,6 +3,7 @@
 #include <json.h>
 #include <libevdev/libevdev.h>
 #include <stdio.h>
+#include <time.h>
 #include <wlr/config.h>
 #include <wlr/types/wlr_content_type_v1.h>
 #include <wlr/types/wlr_output.h>
@@ -820,6 +821,33 @@
 #endif
 }
 
+/* WHY: pre-transaction geometry must be measured from the actual source node.
+ * CONTRACT: this private trace reads the mapped target only during get_tree.
+ * INVARIANT: no scene state, buffer reference or transaction is changed. */
+struct target_trace_context {
+    struct sway_container *container;
+};
+
+static void trace_target_source(struct wlr_scene_buffer *buffer,
+        int sx, int sy, void *data) {
+    struct target_trace_context *ctx = data;
+    int gx = 0, gy = 0;
+    bool valid = wlr_scene_node_coords(&buffer->node, &gx, &gy);
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    fprintf(stderr, "TARGET_SOURCE ns=%lld con=%p con_id=%zu view=%p node=%p buffer=%p parent=%p global_valid=%d global=%d,%d local=%d,%d source_size=%d,%d dest=%d,%d src_box=%.3f,%.3f,%.3f,%.3f transform=%d enabled=%d\n",
+        (long long)ts.tv_sec * 1000000000LL + ts.tv_nsec,
+        (void *)ctx->container, ctx->container->node.id,
+        (void *)ctx->container->view, (void *)&buffer->node,
+        (void *)buffer->buffer, (void *)buffer->node.parent, valid, gx, gy, sx, sy,
+        buffer->buffer ? buffer->buffer->width : 0,
+        buffer->buffer ? buffer->buffer->height : 0,
+        buffer->dst_width, buffer->dst_height,
+        buffer->src_box.x, buffer->src_box.y,
+        buffer->src_box.width, buffer->src_box.height,
+        buffer->transform, buffer->node.enabled);
+}
+
 static void ipc_json_describe_container(struct sway_container *c, json_object *object) {
 	json_object_object_add(object, "name",
 			c->title ? json_object_new_string(c->title) : NULL);
@@ -886,6 +914,14 @@
 	json_object_object_add(object, "marks", marks);
 
 	if (c->view) {
+        const char *app_id = view_get_app_id(c->view);
+        if (getenv("SAVED_TARGET_TRACE") && app_id &&
+                strcmp(app_id, "org.mosaic.SavedBufferProbe") == 0 &&
+                c->view->content_tree) {
+            struct target_trace_context ctx = {.container = c};
+            wlr_scene_node_for_each_buffer(&c->view->content_tree->node,
+                trace_target_source, &ctx);
+        }
 		ipc_json_describe_view(c, object);
 	}
 }
--- a/sway/tree/view.c
+++ b/sway/tree/view.c
@@ -1328,6 +1328,23 @@
 		buffer->buffer ? buffer->buffer->height : 0, sx, sy, (void *)sbuf->node.parent);
 }
 
+/* WHY: copied local offsets cannot prove a global boundary crossing.
+ * CONTRACT: private observation only; the node and buffer remain borrowed.
+ * INVARIANT: no buffer lock or scene mutation is introduced. */
+static void trace_target_saved_buffer(struct wlr_scene_buffer *buffer,
+        int sx, int sy, void *data) {
+    struct sway_view *view = data;
+    int gx = 0, gy = 0;
+    bool valid = wlr_scene_node_coords(&buffer->node, &gx, &gy);
+    fprintf(stderr, "TARGET_SAVED ns=%lld view=%p con=%p node=%p buffer=%p parent=%p global_valid=%d global=%d,%d local=%d,%d source_size=%d,%d dest=%d,%d enabled=%d\n",
+        saved_ns(), (void *)view, (void *)view->container,
+        (void *)&buffer->node, (void *)buffer->buffer,
+        (void *)buffer->node.parent, valid, gx, gy, sx, sy,
+        buffer->buffer ? buffer->buffer->width : 0,
+        buffer->buffer ? buffer->buffer->height : 0,
+        buffer->dst_width, buffer->dst_height, buffer->node.enabled);
+}
+
 void view_save_buffer(struct sway_view *view) {
 	if (!sway_assert(!view->saved_surface_tree, "Didn't expect saved buffer")) {
 		view_remove_saved_buffer(view);
@@ -1354,6 +1371,9 @@
 
 	wlr_scene_node_set_enabled(&view->content_tree->node, false);
 	wlr_scene_node_set_enabled(&view->saved_surface_tree->node, true);
+    /* CONTRACT: measure the actual saved node after enabling the tree. */
+    wlr_scene_node_for_each_buffer(&view->saved_surface_tree->node,
+        trace_target_saved_buffer, view);
 	fprintf(stderr, "SB_ENABLE ns=%lld view=%p tree=%p content_enabled=%d saved_enabled=%d\n",
 		saved_ns(), (void *)view, (void *)view->saved_surface_tree,
 		view->content_tree->node.enabled, view->saved_surface_tree->node.enabled);